Line 8-inch-square pan with foil (most easily lined by first inverting pan, shaping foil over it, then placing foil shape into pan). Gently press foil into place, especially in corners. Butter foil, then coat lightly with flour, tapping out excess.
Cream butter and sugar until light and fluffy. Add eggs and vanilla, beating until smooth. Stir in melted chocolate.
Sift together cake flour, baking powder and salt. Add to batter. Mix until smooth. Stir in walnuts and 2/3 cup chocolate pieces.
Transfer half of batter to prepared pan, spreading evenly. Freeze until firm, about 10 minutes. Pour Caramel Layer over brownie layer, using back of spoon to spread over entire surface, little thinner layer at edges than at center of pan. Refreeze until caramel layer is firm, about 5 minutes. Spread remaining brownie batter evenly over caramel.
Bake in center of oven at 325 degrees until brownies come away slightly from sides of foil and wood pick inserted in center comes out with sheer coating of melted chocolate and caramel but no thick batter, about 40 minutes. Cool completely on rack. Refrigerate at least 4 hours or overnight, covered airtight. Spread Glaze over brownies. Chill, covered with foil.
Remove brownies from pan, using foil. Place brownies on cutting board. Discard foil. Cut brownies into 1-inch squares. May be cut and kept refrigerated, wrapped airtight, for as long as 2 days or frozen as long as 1 month. Thaw in airtight container in refrigerator. Serve chilled. Makes 36 (1-inch) squares.
14 ounces caramels
1 tablespoon unsalted butter
3 tablespoons whipping cream
Gently melt caramels and 1 tablespoon butter with cream in saucepan over low heat, stirring often until smooth. Or heat in microwave oven at MEDIUM (50% power) until melted, about 3 to 4 minutes, stirring often until smooth.
2 tablespoons unsalted butter
3 ounces semisweet chocolate
2 tablespoons whipping cream, about
1/3 cup powdered sugar, sifted
1 teaspoon vanilla
Combine butter and chocolate in top of double boiler and melt over simmering water. Or microwave to melt at lowest setting, stirring often. Do not overcook, or glaze will be gritty. Remove from heat. Add salt, 1 tablespoon cream, powdered sugar and vanilla. Stir gently to combine. Stir in additional cream as needed for desired texture.